Alternator



ay 6, 1969 MONPETIT ET ALTERNATOR I of 4 Sheet Filed Jan. 25, 1967 E m 9 v w s F 2 .3 a NN L. MONPETIT ET AL ALTERNATOR Sheet Filed Jan. 23, 1967 L. MONPETIT ET AL ALTERNATOR Sheet of 4 Filed Jan. 23. 1967 a v M Q a a N \X? Q m a 1 ALTERNATOR Sheet Filed Jan. 23. 1967 United States Patent 4 Int. Cl. 1102 9714; H02k 33/00 US. Cl. 2901 19 Claims ABSTRACT OF THE DISCLOSURE Alternator in which the prime mover includes an internal combustion engine of the free piston .type whose piston rod carries the field. The latter is reciprocable re1ative to the armature which is secured to fixed ways for followers provided on the field. The field comprises two or more. packages of metallic laminations and clamping means for securing such packages directly to the piston rod. r 1

Cross-reference to related application Y A somewhat similar alternator is disclosed in the copending application Ser. No. 585,832, now Patent No.

3,370,576 of Huber, filed-on Oct. 11, 1966 for A Free A Piston Motor and aSsigned'to the same .assignee.

Background of the invention The present invention relates to alternators in general, and more particularly to' improvements in alternators of the type wherein the field is connected to the movable portion of the prime mover and reciprocates with reference to; the armature.

."French Patent No. 1,104,158 discloses an alternator wherein the'prirne mover comprises (a) an internal combustion engine'having a piston which is reciprocable'in a fixed cylinder and (b) a hydraulic or pneumatic restoring spring also including a cylinder for a piston which can returnthe piston of the internal combustion engine" to one of its end positions upon completion of a power stroke. Thefieid comprises a blade constituted by a frame includinga package of sheet metal laminations separated from'each other by insulating foils. The blade transforms mechanical" energy into electrical energy in response-to reciprocation with reference to a stationary armature-'whereby'the" blade cuts the lines of force betw'een the poles of the armature. In the alternat'or'of the aforesaid French patent, the blade is aflixed to the piston Oftheengine-and to the piston of the restoring spring bymeans of screws which also serve to clamp the softiron laminations; Since the blade should be electrically open'; the screws u and the laminations must'be insulated from the piston rod. A serious drawback of such conventional alternators isthat, though'the blade'must take up considerable stresses, its resistance to buckling is low and themechanical connection between its insulating means and themovable portion of the prime mover is too weak. Machining of the blade parts is difiicult, mainly because of the-two-dimensional form of the blade and in'view of necessaryv tolerances to compensate for thermal expansion. Furthermore, the magnetic circuit of the'alternator is heavy, bulky and therefore hard-to-handle. The weight increases with the power developed for a given oscillation frequency/On the other hand, precise guiding of the blade is of utmost importance because, while moving in the air gap, the field is subjected to the action of considerable magnetic forces. The clearances for the blade ice and thermal expansion when the alternator is in actual use.

Accordingly, it is an important object of the present invention to provide an improved alternator which avoids the drawbacks of the aforementioned conventional alternators.

Another object of the invention is to provide an improved electromechanical unit for use in alternators of the type wherein the field is reciprocated by a prime mover which includes an internal combustion engine of the free piston type and a hydraulic or pneumatic restoring spring.

A further object of the invention is to provide a novel and improved connection between the field and the reciprocatory portion of the prime mover in an engineoperated variable-reluctance alternator.

An additional object of the invention is to provide a novel and improved mounting for the armature of the above outlined alternator.

Still another object of the invention is to provide novel guide means for the field of the improved alternator.

A concomitant object of the invention is to provide an alternator whose parts are readily accessible in response to partialdismantling.

Summary of the invention Our invention resides in the provision of an alternator including a prime mover which comprises a fixed portion and a reciprocable portion, the latter including a pair of pistons which respectively form part of an internal combustion engine and a fluid-operated restoring spring, and a piston rod rigid with the two pistons, an armature adjacent to the path of movement of the piston rod, and a field which is connected directly with the piston rod.

The field comprises two or more packages of laminations and clamping means for fixing such packages to the piston rod.

In accordance with an important feature of the invention, the alternator further comprises fixed ways adjacent to the field and follower means provided on the clamping means and co-operating with the ways to guide the field during movement with the reciprocable portion of the from each other by'foils of insulating material;

must be small, i.e., just suflicient to account for stresses prime mover. v

The novel features which'are considered as characteristic of the invention are set forth in particular'in the ap pended claims. The improved alternator itself, however, both as to its construction and 'its mode of operation, together with additional features and advantages thereof, will be best understood'upon perusal of the following detailed. description of certain specific embodiments with reference to the accompanying drawing.

\ Brief description of the drawing. FIG. 1, is an axial section through an alternator which embodies one form of our invention and whose field comprises two packages 'of soft-iron laminations separated FIG. 2 is a transverse vertical section taken along the line a-a ofFIG. 1; u

FIG. 3 is a longitudinal axial section taken at right angles ,to the plane of FIG. 1, the component parts of the armature. being shown in two different positions one of which is indicated by phantom lines;

FIG. 4 is a fragmentary transverse vertical section taken along the line bbof FIG. 1; I FIG. 5 is a fragmentary longitudinal sectional'view of a modified alternator;

FIG; 6 is a transverse line c--c of FIG. 5; 7

FIG. 7 is a fragmentary longitudinal sectional view of a third alternator;

vertical. section taken along the Description the preferred embodiments Referring first to FIGS. 1 to 4, there is shown an alternator which comprises a prime mover, a two-piece field which is re 'ciprocated by the prime mover, and a stationary armature. The prime mover comprises a fixed portion including two coaxial cylinders 1, 2 and a reciprocable portion including a free piston 3 which is reciprocable in the cylinder 1, a piston 4 which is reciprocable in the cylinder 2, and an elongated piston rod 22 which is rigid with the pistons 3, 4 and carries the field. The cylinder 1 and the piston 3 form part of an internal combustion engine which further comprises scavenging ports 5, exhaust ports 6 and injectors 7. The left-hand piston 3 of FIG. 1 forms part of a prime mover for a second alternator which is a mirror image of the illustrated alternator (see the aforementioned application Ser. No. 585,832 of Huber). The cylinder 2 and piston 4 constitute component parts of a fluid-operated restoring spring which moves the right-hand piston 3 of FIG. 1 back to its left-hand end position. The two cylinders are sealed from each other by a stufiing box 8 which surrounds an intermediate portion of the piston rod 22.

The right-hand end of the cylinder 2 is closed by an annular cover 9 having a hub 10 for a stuffing box and an annular bearing 11 for the piston rod 22. The bearing 11 cooperates with the right-hand piston 3 to prevent wobbling'(lateral movements) of the piston rod 22 in the plane ofFIG. 1 but is movable'with the piston rod laterally in the plane of FIG. 3, i.e., at right angles to the plane of FIG. 1. As shown in FIG. 4, the hub 10 is formed with a non-circular passage 10' bounded by two concave and two flat internal surfaces and its fiat surfaces guide flats or facets 11' of the bearing 11. The bore of the bearing 11 receives an intermediate portion of the piston rod 22 which latter is slidable therein.

The field comprises two packages of soft-iron laminations 16 which are disposed diametrically opposite each other, and clamping means including two axially spaced straps 1Q, 15. Each of these straps extends through a diametral slot of the piston rod 22 and the strap is biased toward the strap 14 by a nut 27 which meshes with an externally threaded end portion of the piston rod. The packages of laminations 16 constitute two blades which share all reciprocating movements of the piston rod 22. The laminations are separated from each other by foils of insulating material.

The two end portions of the strap 14 carry pivots 14 for two block-shaped followers or shoes 13 of rectangular outline. Each of these followers is slidably guided in channels 12 provided therefor in rigid ways constituted by two guide rods 12 affixed to the cover 9, i.e., to the stationary portion of the prime mover. The mounting of guide rods 12 is such that their channels 12 are exactly parallel to the common axis of the fixed cylinders 1 and 2. The followers 13 are movable up and down, as viewed in FIG. 1, i.e., at right angles to the directions in which the bearing 10 is movable in the passage 10' of the hub 10. Each of these followers has two parallel faces whose planes extend substantially radially of the axis of the piston rod 22.

In the illustrated embodiment, the guide rods or ways I 12 also serve to support the armature of the alternator in such a way that the components of the armature are movable between the solid-line operative positions (adjacent to the path of movement of laminations 16) and the broken-line in-operative positions shown in FIG. 3. The armature comprises iron laminations 18, 1'8, exciter coils 28, 28' of copper, and 'U-shaped positioning elements 19 made of sheet metal or the like. The laminations 1'8, 18' are assembled into packages (see FIG. 3) and are traversed by tie rods 17 carrying spacer sleeves or distancing members 26. The tie rods 17 also pass through the positioning members 19 each of which has two legs 19' provided with concave notches or recesses 19" receiving portions of the guide rods 12 in a manner as shown in FIG. 2. Bolts 20 connect the legs 19' of adjoining positioning members 19 so that each part of such positioning members forms a substantially hexagonal frame best shown in FIG. 2.

Hinges 25 connect the components of the armature to the cover 9 (and hence to the guide rods 12) in a manner as shown in FIG. 3. Each of these hinges comprises a first pintle 23 which is mounted on the cover 9 and a second pintle 24 which is mounted on the anmature. When the bolts 20 are removed, the two halves of the armature (each ihcluding two packages of laminations 18 or 18, two tie rods 17 and three positioning members 19) can be swung to the broken-line positions of FIG. 3 so that the laminations 16 of the field are readily accessible for inspection and/ or dismantling. With reference to FIG. 1, the axes of the pintles 23, 24 are vertical, i.e., the two halves of the armature are pivotable in a horizontal plane. On movement of such halves to the broken-line positions of FIG. 3, the right-hand end face of the prime mover is fully exposed and the operators can gain access to the cover 9, pistons 3, 4 and other elements which are difiicult to reach when the armature is held in operative position.

FIGS. 5 and 6illustrate a portion of a second alternator wherein the strap 14" of the clamping means carries cylindrical followers or blocks 13, 13" slidable in complementary channels provided therefor in the ways or guide rods 12". The lower follower 13' is pivotally secured, without play, to the adjoining end portion of the strap 14" by a horizontal pivot pin 32 whose axis is normal to and crosses in space the axis of the piston rod 22. In this way, the follower 13' prevents uncontrolled movements of the field in the plane of FIG. 5 and also in the plane of FIG. 6. The upper follower 13" is slidable vertically in a fork 33 forming the upper end portion of the strap 14". The prongs of the fork 33 straddle two flats or facets of a pin 34 which can move radially of the piston rod 22 and carries or is integral with the upper follower 13".

The cover 9" of the prime mover carries a conventional stufling box 35 which replaces the stuffing box and the bearing 11 in the hub 10 of the cover 9 shown in FIG. 1. The fork 33 and pin 34 replace the bearing 11. 50

FIGS. 7, 8 and 10 illustrate a portion of a third alternator whose field comprises three equidistant blades each including a package of soft-iron laminations 16 located ina plane which includes the axis of the piston rod 22". The piston 3 is rigid with the piston rod 22" which latter carries a ring-shaped flange 33 and comprises a cylindrical portion 36 serving as a core for the field. The core 36 is surrounded by a sleeve 39 having in its periphery three axially extending grooves for the radially innermost portions of the laminations 16. The straps 14', 15' are disposed at the respective axial ends of such laminations and their outer end portions are fixed to the ends of tie rods 38. The strap 14 :bears against the flange 33 -andthe strap 15' is biased by the nut 27 which meshes with'the end portion of the core 36. At least one end of each tie rod 38 is electrically insulated from the strap 14 or 15' to prevent electrical loop formation. The tie rods 38 are outwardly adjacent to U-shaped retainers or'stiffeners 37 which accommodate the radially outermost portions of the respective laminations 16 and are clamped between the straps 14', 15.

The free end portion 4" of the piston rod 22" .constitutes the piston of the restoring spring. Thus, and as clearly shown in FIG. 7, the field is located between the piston 3 of the engine and the piston 4 of the restoring spring. The restoring spring is preferably operated by a hydraulic pressure medium.

FIG. shows that the armature of the third alternator comprises three groups of laminations 18 and exciter coils 7'8.

FIGS. 9 and 11 show portions of an alternator which is analogous to the one shown in FIGS. 7, 8 and 10 but whose field comprises only two packages of laminations 16 located diametrically opposite each other. The armature comprises two groups of laminations and windings 28.

The ways and followers for the third and fourth alternators have been omitted for the sake of clarity.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected -by Letters Patent is set forth in the appended claims:

1. An alternator, comprising a prime mover including a fixed portion and a reciprocable portion; an armature adjacent to said reciprocable portion; a field afiixed to said reciprocable portion to move therewith relative to said armature; fixed ways adjacent to said field; and follower means provided on said field and cooperating with said ways to guide said field during movement with said reciprocable portion.

2. An alternator as defined in claim 1, wherein said armature is supported by said fixed portion.

3. An alternator as defined in claim 1, wherein said reciprocable portion comprises a piston rod and said field comprises at least two packages of metallic laminations and clamping means fixing said packages to said piston rod.

4. An alternator as defined in claim 3, wherein said clamping means comprises a pair of axially spaced strap means mounted on said piston rod, said follower means being provided on at least one of said strap means and said packages being disposed between said strap means.

5. An alternator as defined in claim 4, wherein said field further comprises biasing means provided on said piston rod and arranged to urge one of said strap means toward the other strap means.

6. An alternator as defined in claim 1, wherein said armature is mounted on said ways.

7. An alternator as defined in claim 6, wherein said armature comprises plural packages of laminations, positioning means for said packages, and means for securing said positioning means to said ways.

8. An alternator as defined in claim 1, further comprising hinge means connecting said armature to the fixed portion of said prime mover for movement between operative and inoperative positions, said field being accessible on movement of the armature to inoperative position.

9. An alternator as defined in claim 1, wherein said prime mover comprises an internal combustion engine having a cylinder which constitutes an element of said fixed portion and a piston which is rigid with said piston rod and is reciprocable in said cylinder, said prime mover further comprising a fluid-operated restoring spring for said piston, said spring including a second cylinder forn ing part of said fixed portion and a second piston reci rocable in said second cylinder and rigid with said pisto rod.

10. An alternator as defined in claim 4, wherein sai one strap means comprises end portions remote froi said piston rod and said follower means comprises block of polygonal outline and pivot means connecting sai blocks to the end portions of said one strap means, sai blocks having freedom of movementwith reference t said ways in a first plane which includes the axis of sai piston rod and further comprising bearing means carrie by said fixed portion for guiding the piston rod witl freedom of movement in a second plane which is norma to said first plane.

11. An alternator as defined in claim 10, wherein sail bearing comprises two facets parallel with said seconl plane and said fixed portion comprises a member receivin; said bearing with limited freedom of movement in sait second plane, said member having internal surfaces abut ting against said facets.

12. An alternator as defined in claim 4, wherein sait one strap means comprises end portions remote from sait piston rod and said follower means comprises cylindrica blocks articulately connected with said end portions, sait ways comprising channel means slidably receiving saic blocks.

13. An alternator as defined in claim 12, wherein one of said blocks is connected with the respective end portion by means of a pivot whose axis is normal to and crosses in space the axis of said piston rod.

14. An alternator as defined in claim 13, wherein another of said blocks has two parallel facets extending substantially radially of said piston rod and the respective end portion is constituted by a fork which receives said last-mentioned block with freedom of movement radially of said piston rod.

15. An alternator as defined in claim 4, wherein the laminations of said packages are insulated from each other by foils and further comprising tie rods connecting said straps to each other, each of said tie rods being electrically insulated from at least one of said straps.

16. An alternator as defined in claim 3, wherein said field comprises three equidistant packages of laminations, said packages being disposed in planes which include the axis of said piston rod.

17. An alternator as defined in claim 9, wherein said field is disposed intermediate said pistons.

18. An alternator as defined in claim 17, wherein said second piston is constituted by an end portion of said piston rod.

19. An alternator as defined in claim 9, wherein said second piston is located intermediate said first piston and said field.

References Cited UNITED STATES PATENTS 1,785,643 l2/l930 Noack et al 310-15 X 3,247,406 4/ 1966 Toesca 3 l0-15 3,337,760 8/1967 Allport 310 -13 ORIS L. RADER, Primary Examiner. W. E. DUNCANSON, JR., Assistant Examiner.

US. Cl. X.R. 310-15 

